Destructive distillation of vegetable matter with caustic and lime



Patented Jan. 24, 1950 DESTRUCTIVE DISTILLATION OF VEGE- TABLE MATTERWITH CAUSTIC AND LIME Jacques Urison, Paris, Philippe de Calignon,Lannemeran, and Gustave Pingard, Thann, France, aslignors to SocletePyreneenne de Carburants ct Solvants, Paris, France, a- Frenchcorporation Application October 30, 1945, Serial No. 625,674 In FranceOctober 19, 1944 Section 1.1mm Law 690, August a, 1946 Patent expiresOctober 19, 1964 2 Claims. (Cl. 202-34) The present invention relates tothedisintegration of celluloso-ligneous matters with a'view to obtainingliquid condensable organic compounds consisting chiefly of products ofketonic character.

The drawing shows a flow sheet illustrating the steps of the method.

Our method comprises a preliminary impregnation, a heating in anautoclave and a pyrolysis treatment, these operations being carried outas follows:

Impregnation is carried out with a view to causing alkalis to penetrateinto the pores, and especially into the capillary network of the matterto be treated, and obtaining a mass which is homogenous at the scale ofthe matter cut into small parts. This homogenizing of the impregnationobviously depends upon the nature of the raw material and the way inwhich it has been divided into small parts (by means of a straw cutter,a crusher, and so on), upon its dryness, the mechanical means used formixing the whole, the temperature, and the pressure.

Impregnation must be carried out at a relatively low temperature,preferably averaging 50 C., at which temperature the vapor tensionsinside the cells will oppose an admissible resistance to penetration ofalkalis by dialysis. The important thing concerning this impregnation isto reach a homogenous state of distribution of the liquid in the solidmaterial without allowing disincrustation, which corresponds to areduction of the free or "active alkali, to make substantial progress. vv

This impregnation must be carried out very carefully, and it isparticularly delicate because the amount of liquid that is used issmallwith respect to the celluloso-ligneous material (from 0.7 to 3 litres ofliquid per kilogram of wood).

The methods used for this impregnation and for checking the efliciencyof the homogenizing are identical to those commonly used in woodimpregnation industry. For instance we may use pressure, vacuum, bothalternately (for elimination of the air that may be entrapped), or anyother suitable means. However, in the present case, the particularlyimportant thing is to avoid bringing .the mixture to temperaturescorresponding to a substantial disincrustation.

Heating is then carried out, for a relatively short time (from 1 to 4hours for instance), in an autoclave in which the temperature of themass is raised to l-180 C. in a very short time, for instanceapproximately from 10 to 15 minutes. In this way, we avoid keeping themass for an appreciable time inside a zone of temperatures for whichonly the incrustant substances are solubilized, and we reach morerapidly the zone of temperatures for which cellulose itself is attacked,same as lignin, in suitable conditions and nea rly simultaneously.

This quick rise of the temperature can be carried out only with a masssuitably impregnated with alkali. Otherwise, that is to say in the caseof a heterogeneous mixture, exothermic phenomena take place, with a.production of gases and even a spontaneous degradation of thecellulosoligneous matter analogous to carbonization.

This heating may be carried out with the apparatus commonly used in themanufacture of paper pulp through the soda process, and the quick riseof temperature may be obtained, under industrial conditions, by aninjection of steam into the autoclave.

After heating, lime, either slaked or unslaked, is added to the mass andthe whole is dried, preferably at a temperature of 160480 0., thistemperature being maintained for some hours after the drying iscompleted. This prolonged drying treatment serves to produce a deeperdegradation of the celluloso-ligneous matters, characterized by areduction of the active alkalinity and of the proportion of organicsubstances that are not scoured.

The uncondensable gases and the vapors that disengage during the heatingand drying treatments, and also the uncondensable gases resulting fromthe pyrolysis treatment, may be used advantageously for sweeping orscavenging the free space of the pyrolysis apparatus, instead of usingfor this operation steam produced especially for this purpose as inknown pyrolysis treatments.

This supplementary production of steam is thus avoided or at leastgreatly reduced and, on the other hand, dilution of the products thatare obtained, as a result of the condensation of said steam, is avoided.

We will now describe two examples of th method according to ourinvention:

3 Example I The following elements are intimately mixed together:

100 kgs. of oaksaw-dust 60 kgs. of caustic soda 60 kgs. of water.

Caustic soda is used under any physical form whatever. Water isintroduced partly in admixture with wood and soda, and the amount ofwater necessary to give the above indicated amounts is added. The massis left alone for 12 hours for impregnation purposes.

The whole is then introduced into a rotary autoclave of a capacity of450 litres, externally heated. The temperature is brought'to 180 C. in aquarter of an hour and this temperature is maintained for 3 hours. Theapparatus is then placed in communication with a vapor accumulator orwith the pyrolysis apparatus and the pressure is allowed to drop to avalue approximating atmospheric pressure. The mixture of organic saltsthat is obtained still contains at this time about 12 percent of organicsubstances not scoured, with respect to the starting material.

120 kgs. of slaked lime are added and the temperature is again broughtto 180 C. This temperature is maintained for 2 hours, while expandingthe vapor into the vapor accumulator.

After this drying treatment, the mixture contains only per cent oforganic substances not scoured.

The whole is pyrolysed in a rotary furnace, of the continuous workingtype, heated from the outside (outlet temperature ranging from 500 to600 0.). The apparatus is swept by a stream of steam and vaporsresulting from the heating and drying treatments.

After condensation, 21 kgs. of liquid valuable products are collected,the weights corresponding to anhydrous products, to wit:

Kgs. Acetone-l-methyl alcohol 5 Light oils (flash point below 220 C.) 9Heavy oils (flash point above 220 C.) 7

If the drying operation is dispensed with, only from 10 to kgs. ofproducts are obtained.

Example II The following elements are intimately mixed together:

100 kgs. of vine-shoots,

50 kgs. of soda, 336 kgs. of water.

The mixing is pursued, at a temperature of 70 C., in a rotary apparatus,for 2 hours. The mass is then introduced into a rotary autoclave. Thetemperature is raised to 170 C. in ten minutes, by introduction oi! livesteam, and this temperature is maintained for two hours. The pressure isthen allowed to drop to a value substantially equal to atmosphericpressure, by elimination of steam.

The proportion of unsecured organic substances in the mass is then aboutper cent of the initial matter.

125 kgs. of unslaked lime are then added and the temperature is broughtto 180, by external heating. This temperature is maintained for 2 hoursand the pressure is caused to drop by elimcontaining:

Kgs. Acetone+methyl alcohol 6 Light oils (flash point below 220 C.) 8.5Heavy oils (flash point above 220 C.) 7.5

These treatments are given merely by way of example and they may bemodified, both concerning the operations in themselves and theparticularbodies that are used, without departing from the spirit of theinvention.

The final residual mass. after pyrolysis, is constituted by sodium andcalcium carbonates, soda, lime, and a residual carbon containing apercentage of hydrogen whichdepends upon the final pyrolysistemperature; This residue may be treated according to the known methodsfor caustificailzion of the amount of COaNaz present in the soda Themixture of calcium carbonate and coal is then calcined, the residualcoal adding itself to the fuel that is supplied. The calcium carbonateis transformed into unslacked lime for being returned into the cycle ofoperations.

The whole of the reagents that have been employed can thus be returnedinto the cycle with the exception of course of the losses due to theoperations.

It. is also possible to recuperate the residual coal and to utilize itas activated com for instance.

This activity depends upon the proportion of hydrogen present thereinand the final temperature.

In a general manner, while we have, in the above description, disclosedwhat we deem to be pyrolysis practical and eflicient embodiments of thepresent invention, it should be well understood that we do not wish tobe limited thereto as there might be changes made therein withoutdeparting from the principle of th present invention as comprehendedwithin the scope of the appended claims.

What we claim is:

1. A method of producing liquid condensable organic-compounds fromvegetable cellulosic material, which comprises impregnating thiscellulosic material with a caustic soda lye at a temperature relativelylow, treating the impregnated material in an autoclave in the presenceof caustic alkali by quickly raising the temperature of the mass up to-180 0., adding lime to the mass, drying at a temperature of 160-180 C.,keeping said mass at this temperature for several hours after the end ofthe drying operation, and treating by pyrolysis.

2. A method of producing liquid condensable organic compounds fromvegetable cellulosicmaterial, which comprises impregnating thiscellulosic material with a caustic soda lye, at a temperature ofapproximately 50 C., treating the impregnated material in an autoclavein the presence of caustic alkali by raising the temperature of the massup to 160-180 C. in 10 to 15 minutes, by injection of live steam intothe autoclave, adding lime to the mass, drying at a temperature of160-180 C., keeping said mass at this temperature for several hoursafter the end of the drying Number Name Date operation, and treating bypyrolysis. 1,298,479 Drewson Mar. 25, 1918 JACQUES URISON. 1,764,249Erlenbach June 17, 1930 PHILIPPE n1: CALIGNON. 1,772,216 Hagglund Aug.5, 1930 GUSTAVE PINGARD. 5 1,879,502 Rinman Sept. 27, 1932 2,177,557Bergstrom Oct. 24, 1939 REFERENCES CITED 2,056,746 Btrupp Oct. 6, 1946The following references are of record in the FOREIGN PATENTS me of thispatent 10 Number Country Date UNITED S A S ATENTs 114,878 Australia Mar.11, 1942 Number Name mt 424,847 Great Britain Mar. 1, 1935 1,202,479Rinman Oct. 24, 1916

1. A METHOD OF PRODUCING LIQUID CONDENSABLE ORGANIC COMPOUNDS FROMVEGETABLE CELLULOSIC MATERIAL, WHICH COMPRISES IMPREGNATING THISCELLULOSIC MATERIAL WITH A CAUSTIC SODA LYE AT A TEMPERATURE RELATIVELYLOW, TREATING THE IMPREGNATED MATERIAL IN AN AUTOCLAVE IN THE PRESENCEOF CAUSTIC ALKALI BY QUICKLY RAISING THE TEMPERATURE OF THE MASS UP TO160-180*C., ADDING LIME TO THE MASS, DRYING AT A TEMPERATURE OF160-180*C., KEEPING SAID MASS AT THIS TEMPERATURE FOR SEVERAL HOURSAFTER THE END OF THE DRYING OPERATION, AND TREATING BY PYROLYSIS.